Just like how the network admins keep a watch on the configuration changes of networking hardware, it is also important to monitor config changes in a virtual environment. While network configuration errors are definitely a nightmare and can cause the network to go down, config errors in a virtualized host or VM can impact all the servers and applications dependent on them. In a virtual environment, most of the repair time is spent on investigating what changed in a system. Unlike network devices whose config files we want to keep in good state and not make changes unless required, the nature of the virtual environment is such that it is dynamic and VMs will be migrating between hosts and clusters, there will be resources provisioned and reallocated constantly. And all this results in configuration changes. Config changes are also possible during routine processes such as software updates, security patches, hot fixes, memory, CPU and disk upgrades. If we are not keeping a track of what is changing in the virtual layer, we wouldn’t be able to diagnose and troubleshoot performance problems easily.
HOW TO DETECT VIRTUALIZATION CONFIGURATION CHANGES?
The best solution is to map the state of your virtual environment and all its components (such as clusters, VMs, hosts and datastores) in accordance with time, and maintain historical status of the map as it evolves and encounters changes. You need to be in a position to compare the current and historical configuration state of a specific VM between different dates and times. And also compare one VM configuration with another over a specific time in consideration. In this way you’ll be able to what has changed and get visibility for troubleshooting config changes.
- Compare configuration of VMs before and after vMotion or live migration
- Monitor whether configuration of a VM has changed over time
- Monitor resource allocation (CPU, memory, disk and network) to VMs as this directly impacts VM configuration
- Monitor VM workload: To meet growing workload the hypervisor can provision more resources to a VM and this could result in a config change
- VM Sprawl: Zombie/stale/inactive VMs present in the virtual environment can cause resource contention amongst the active VMs and, in turn, cause config changes at the host level
Virtualization config changes are part of the package and there are bound to be changes as VMs keep moving and migrating. This doesn’t mean VM migration is risky. Flexibility of VM movement is one of the benefits achieved with server virtualization and we should leverage it. Employ the right virtualization management tool to ensure your virtualization environment is mapped, and configuration changes are captured and reported!